Annual statistics in the United States suggest that there are 1.6 million homeless youths (HY)1,2 and an estimated 1.4 million active gang members.3 Experiences of homelessness and gang membership are known determinants of negative behavioral health outcomes,4-10 including the most frequently examined potential correlates of HIV risk behaviors: substance use and risky sexual behavior. Although seemingly disparate occurrences, homelessness and gang involvement intersect.11-13 Previous research has found that approximately 15% of HY currently identify as gang members and up to 32% have ever been gang affiliated.13 However, very little is known about HY gang members and closely affiliated peers. To better understand this population, the proposed study will explore HIV risk behaviors among gang-involved HY related to social networks. The study's goals include drastically increasing knowledge regarding HY gang involvement using an explanatory sequential mixed-methods approach. During the first phase of the proposed study, quantitative survey data and social network data from an NIMH-funded R01 study (MH903336; PI: Rice) with HY will be used to identify associations between HIV risk behaviors and social networks among gang-involved HY (self- identified members and affiliates). In Phase 2, purposeful sampling methods will be used to identify and select high risk gang-involved HY to participate in semi-structured life history calendar (LHC) interviews. The LHC approach will be used to contextualize and expand on the Phase 1 findings and to develop a theoretical framework to understand the HIV risk gang-involved HY. The rigor of using multiple sources of data (quantitative, social network, and LHC) will provide a unique contribution to the literature and increase our understanding of gang involvement and HIV risk among homeless youths. With the assistance of a community advisory board, these findings will be used to inform new directions in HY interventions; specifically what network-level interventions could be adapted to prevent gang-related HIV risks in the HY population.